NBC and the Wall Street Journal, in partnership with a few more final polls from some second-tier swing states that Barack Obama won in 2008 but might lose in 2012.  The Marist polls gives Obama some good news in Iowa, but warnings about New Hampshire and traditionally-safe Wisconsin.  All three polls suggest that momentum remains on Mitt Romney’s side:

Less than a week before Election Day, President Barack Obama holds a statistically significant lead over Republican nominee Mitt Romney in the battleground of Iowa, while the two candidates are locked in tight races in New Hampshire and Wisconsin, according to new NBC News/Wall Street Journal/Marist polls.

In Iowa, Obama is ahead by six points among likely voters, 50 percent to 44 percent, which is down from his eight-point lead earlier this month.

In Wisconsin, the president edges Romney by three points, 49 percent to 46 percent, which is within the survey’s margin of error. That’s also down from Obama’s six-point lead earlier this month.

Let’s take these one at a time, straight from the poll data.  In Iowa, the sample D/R/I is 34/31/34, very similar to 2008’s 34/33/33, but off a bit from 2010’s 31/35/34.  There isn’t that much difference between these three models, but there is some, particularly in undersampling Republicans.  However, this poll finds Obama winning independents outside the MOE, 47/39, but far short of his 2008 margin of 56/41.  Independents also have a better opinion of Obama (50/41) than Romney (38/48), although that’s not reflected in job approval (44/45).  If Marist’s poll is accurate, Romney will have a tough time winning Iowa.

The news is better in Wisconsin, and not just from the toplines:

Among likely voters in Wisconsin, including those who are undecided yet leaning toward a candidate and those who voted absentee, President Barack Obama and Vice President Joe Biden receive the support of 49% to 46% for Mitt Romney and Paul Ryan.  Two percent back another candidate, and 3% are undecided.

The sample in this case is less solid. The D/R/I is 34/29/35; in 2008, turnout was 39/33/29, and I’m pretty sure Republicans aren’t going to underperform that outcome.  In 2010, it was 37/36/28, and in June’s recall election, it was 34/35/31.  I think in this case it’s Obama who’s in trouble, although he has a narrow lead with independents in Wisconsin, 48/44.  Obama won them by 19 in 2008.

Guessing outcomes in New Hampshire is almost always a fool’s errand, but we’ll take a look anyway. Obama’s up 49/47 in a 27/26/47 sample.  In 2008, it was almost identical at 29/27/45, and in 2010 27/30/44.  Independents obviously drive elections in the Granite State more than any other state, and indies give a slight edge to Romney, 47/46. Obama won them by 20 in 2008.

Overall, I’d say that while the toplines look decent for Obama and the samples look arguably solid, those numbers for independents should be a big, big worry.  Obama has lost most of his double-digit edges among indies in all three states, and is in a virtual tie in Wisconsin and New Hampshire with Romney in those demos. With Republican enthusiasm waxing and Democratic enthusiasm waning, these second-tier swing states could break Obama’s hopes of winning a second term.

Update: For what it’s worth, the University of Iowa’s Hawkeye Poll shows a virtual dead heat among likely voters, with Romney having an edge of less than a point — but note the levels of support for the incumbent (via Guy Benson):

With the presidential election less than one week away, it’s still a close race in Iowa, a key swing state. Mitt Romney has a slight edge over Barack Obama among likely voters in the state, according to a University of Iowa Hawkeye Poll released today. The Hawkeye Poll is a teaching, research, and service project of the Department of Political Science in the College of Liberal Arts and Sciences (CLAS).

Obama has a slight lead in Iowa among all respondents, with 42.7 percent of the vote to 41.0 percent for Romney, with 10.5 percent undecided and 5.8 percent preferring a third party candidate. Romney leads among likely voters, though, with 45.2 percent of the vote compared to 44.4 percent for Obama, with 6 percent undecided and 4.3 percent preferring a third party candidate. The margin of error for the survey of 320 Iowans is 5.6 percent.

“Our results show Romney making advances and perhaps taking the lead in Iowa, and that the race continues to be close and within the margin of error,” says Frederick Boehmke, associate professor of political science in the UI CLAS and faculty adviser of the Hawkeye Poll. “It appears that the final result will be determined by each campaign’s ability to turn out supporters and to capture the votes of those last few undecided voters.”

They show Obama with a slight edge among independents, 41.9/40.2, but both that and the overall level of support are very bad numbers for an incumbent.  If Obama hasn’t gotten above 45% five days before the election, don’t expect those numbers to improve on Election Night more than a point or two.